Ultrastructural glomerular findings in cryoglobulinemic glomerulonephritis.

Thirty-three renal biopsies of patients affected by cryoglobulinemic glomerulonephritis (CRYGN) were investigated by electron microscopy, paying particular attention to the nature of cells responsible of glomerular hypercellularity, the presence and site of electron-dense deposits and their ultrastructural characteristics. Personal as well as literature data suggest (a) diffuse glomerular hypercellularity found in most cases of CRYGN is mainly due to polymorphonuclear leukocytes and even more to monocyte exudation; (b) the interposition of the latter cell type in the glomerular capillary wall is the main responsible cause of the frequent occurrence of the membranoproliferative pattern in CRYGN, and (c) peculiar structures found in the electron dense deposits are characteristic of CRYGN and related to cryoglobulin composition. Electron microscopy therefore seems to be a valuable diagnostic procedure for this type of glomerulonephritis.